a(n) = Sum_{k=1..n} k * lcm(k,n).

Terms

a(0) =1a(1) =6a(2) =24a(3) =64a(4) =175a(5) =270a(6) =686a(7) =928a(8) =1647a(9) =2150a(10) =4356a(11) =3792a(12) =8619a(13) =8526a(14) =11250a(15) =14592a(16) =25721a(17) =19926a(18) =40432a(19) =31200a(20) =44835a(21) =53966a(22) =87814a(23) =58272a(24) =108125a(25) =106470a(26) =132678a(27) =124656a(28) =224547a(29) =132750